Which was the main cause of the great migration to the united states in the late 1800s?

The discovery of America led to a great  power struggle for control of the new lands primarily between the three most powerful countries in Western Europe at the time: Spain, England, France. These European countries financed the voyages of the early explorers for many reasons. To increase their lands and build great European Empires and to increase the wealth of the 'Mother Country' by exploiting the natural resources of the new lands - the search began for gold, silver and spices. To increase opportunities for trade and to spread the Christian religion. That is what I managed to find online. Hope, it will help you somehow. And if you need the help to structure it all, please, go to the professional service as Marvelous essay service and let them do this job for you. 

i do believe its (d) it allowed the government to offer pioneers sixty acres of western land if they lived on it and made improvements to it.

explanation: signed into law in may 1862, the homestead act opened up settlement in the western united states, allowing any american, including freed slaves, to put in a claim for up to 160 free acres of federal land. by the end of the civil war, 15,000 homestead claims had been established, and more followed in the postwar years